Sunscreen formulation

ABSTRACT

The present application relates to sunscreen formulations, including foamable sunscreen formulations, that comprise zinc oxide and titanium dioxide particles, suitably in the size range of about 1-100 nm. The compositions suitably produce a minimal residual whitening effect when applied to a skin surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/387,709, filed Dec. 22, 2016, pending, which is acontinuation of U.S. patent application Ser. No. 14/539,217, filed Nov.12, 2014, now U.S. Pat. No. 9,561,159, issued Feb. 7, 2017, which is acontinuation of U.S. patent application Ser. No. 13/648,707, filed Oct.10, 2012, now U.S. Pat. No. 8,911,754, issued Dec. 16, 2014, whichclaims the benefit of U.S. Provisional Patent Application No.61/545,848, filed Oct. 11, 2011, the disclosures of each of which areincorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present application relates to sunscreen formulations, includingfoamable sunscreen formulations, that comprise zinc oxide and titaniumdioxide particles, suitably in the size range of about 1-100 nm. Thecompositions suitably produce a minimal residual whitening effect whenapplied to a skin surface.

Background of the Invention

More than 1 million Americans are diagnosed with skin cancer each year,and many more with precancerous conditions. These numbers continue toincrease, not only in the United States, but worldwide. Several factorsappear to be responsible for this alarming rise in skin cancer. Thecontinual erosion of the earth's ozone layer due to pollution results inless available ozone protection than was afforded previous generations.Also, unlike previous generations, today there are over 400 medicationsprescribed that leave patients with an increased sensitivity to sunexposure and a heightened susceptibility to sun damage. Longer lifespanis also a contributing factor. Greater awareness, increased patientconcern and better diagnosis may help to decrease this alarming rise inthe rate of skin cancer.

Perhaps the most important factor in the rise of skin cancer rates isincreased exposure to the ultraviolet A (UVA) wavelength, which istypically defined as 320 to 400 nanometers (nm) in the light spectrum(see FIG. 1). Previously thought of as harmless, this wavelength rangeis now known to contribute significantly to skin damage, skin cancer,DNA damage and Immune system suppression. UVA rays penetrate the skindeeper and, unlike UVB rays (defined as the range of 290 to 320 nm,which cause initial redness and burning), damage from UVA rays is notimmediately detected. Because UVA rays remain constant throughout theyear and during the day, we are exposed to them continuously.

Sunscreen products are traditionally delivered to the skin in the formof creams, lotions, gels and more recently, by means of aerosol spraysor mists. Delivery of particles of titanium dioxide and/or zinc oxide bymeans of a spray or mist may create an inhalation hazard duringapplication across the open air. Consequently, aerosol spray sunscreenscurrently use organic chemical sunscreen filters, which are solubilizedin the inactive ingredients prior to delivery to the skin, but thepossibility of inhalation of the sunscreen product remains.

There exists therefore a need for a readily dispensed sunscreenformulation that is easily applied to the skin, reduces or eliminatespossible product inhalation, and maintains a uniform compositionthroughout the formulation, particularly when utilizing particulatesunscreens, e.g., zinc oxide and/or titanium dioxide.

SUMMARY OF PREFERRED EMBODIMENTS

The needs identified above are met by the present application.

In embodiments, foamable sunscreen formulations are provided. Exemplaryformulations comprise zinc oxide particles, titanium dioxide particles,about 0.1% to about 10% emulsion stabilizer, about 0.1% to about 25%skin conditioner, about 0.1% to about 10% emulsifier, about 0.1% toabout 10% suspending agent and the remainder water. Suitably, theamounts and particle sizes of the zinc oxide and the titanium dioxideare selected so as to produce a minimal residual whitening effect whenapplied to a skin surface.

In embodiments, the emulsion stabilizer is a naturally derived gam or amodified gum or natural mineral. Exemplary emulsion stabilizers includeacacia, cellulose, crystalline cellulose, gellan, guar, locust (carob)bean, xanthan gums, magnesium aluminum silicate, bentonite and hectoriteclays and/or combinations thereof.

Exemplary skin conditioners/emollients include adipate esters, alkylbenzoates, fatty acid esters of C₈ or greater, esterified erucates,laurates, neopentanoates, salicylates, stearates, triglycerides,carbonates, glycols, glycerin, mineral oils and combinations thereof.

Exemplary emulsifiers include polysorbates, fatty acids and theiralkaline salts, ethoxylated fatty acids and their alkaline salts, andsubstituted glucosides. Exemplary suspending agents typically includehydroxystearic acid, polyhydroxystearic acid, sodium polyacrylatepolymers, methyl methacrylate crosspolymers and combinations thereof.

In embodiments, the formulations further comprise about 0.1% to about10% film former for added water resistance, including film formers suchalkyl methacrylate acid copolymers, acrylates/C₁₂₋₂₂ alkyl methacrylatecopolymer, acrylates/octylacrylamide copolymer, polyamide-3,polyurethane-2, polyurethane-34, polyurethane-35, and co-polymers ofeach, vinyl pyrollidone/eicosene copolymers, tricontanyl/polyvinylpyrollidone, dimethicone substituted polyacrylates and combinationsthereof.

In further embodiments, foamable sunscreen formulations are providedchat comprise about 1% to about 25% zinc oxide particles having aprimary particle size of less than about 50 nm, about 1% to about 25%titanium dioxide particles having a primary particle size of less thanabout 50 nm, about 0.1% to about 5% emulsion stabilizer, about 0.1% toabout 25% skin conditioner, about 1% to about 10% emulsifier, about 0.1%to about 10% suspending agent and the remainder water.

In additional embodiments, provided herein is a foamable sunscreenformulation comprising about 9% to about 11% zinc oxide particles havinga primary particle size of about 20 nm, about 2% to about 4% titaniumdioxide particles having a primary particle size of about 30 nm, about0.5% to about 5.0% emulsion stabilizer, about 15% to about 25% skinconditioner, about 2.5% to about 4.5% emulsifier, about 3.5% to about5.5% suspending agent about 1% to about 2.5% film former and theremainder water.

In still further embodiments, a foamable sunscreen formulation isprovided herein that comprises about 10% zinc oxide particles having aprimary particle size of about 20 nm, about 3% titanium dioxideparticles having a primary particle size of about 30 nm, about 1%microcrystalline cellulose and about 0.2% cellulose gum, about 16%C₁₂₋₁₅ alkyl benzoate, about 1% octyldodecyl neopentanoate, about 1%butyl octyl salicylate, about 1.2% glyceryl stearate, about 0.5%ceteareth-20, and about 2% polysorbate 80, about 1.8% polyhydroxystearicacid and about 2.7% methyl methacrylate crosspolymer, about 0.8%polyurethane-2, about 0.3% polymethyl methacrylate and about 0.6%tricontanyl PVP film and about 50% to about 60% water and apreservative.

Also provided are methods of preventing sun damage to a patient's skinsurface, comprising applying the foamable sunscreen formulationsdescribed herein to a patient's skin.

Further embodiments, features, and advantages of the embodiments, aswell as the structure and operation of the various embodiments, aredescribed in detail below.

DESCRIPTION OF THE FIGURES

FIG. 1 shows a diagram of the light spectrum from sunlight.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It should be appreciated that the particular implementations shown anddescribed herein are examples and are not intended to otherwise limitthe scope of the application in any way.

The published patents, patent applications, websites, company names, andscientific literature referred to herein are hereby incorporated byreference in their entirety to the same extent as if each wasspecifically and individually indicated to be incorporated by reference.Any conflict between any reference cited herein and the specificteachings of this specification shall be resolved in favor of thelatter. Likewise, any conflict between an art-understood definition of aword or phrase and a definition of the word or phrase as specificallytaught in this specification shall be resolved in favor of the latter.

As used in this specification, the singular forms “a,” “an” and “the”specifically also encompass the plural forms of the terms to which theyrefer, unless the content clearly dictates otherwise. The term “about”is used herein to mean approximately, in the region of, roughly, oraround. When the term “about” is used in conjunction with a numericalrange, it modifies that range by extending the boundaries above andbelow the numerical values set forth. In general, the term “about” isused herein to modify a numerical value above and below the stated valueby a variance of 20%. It should be understood that use of the term“about” also includes the specifically recited amount.

Technical and scientific terms used herein have the meaning commonlyunderstood by one of skill in the art to which the present applicationpertains, unless otherwise defined. Reference is made herein to variousmethodologies and materials known to those of skill in the art.

In embodiments, the application provides foamable sunscreenformulations. In exemplary embodiments, the formulations comprise zincoxide particles and/or titanium dioxide particles, and suitably bothzinc oxide and titanium dioxide particles.

As used herein, the term “foamable” or “foam” as it relates to aformulation refers to an aqueous emulsion system, that upon actuationwith an aerosol, produces a stabilized, homogenous, expandablecomposition that breaks easily upon shearing. The terms foams andfoamable formulations are used interchangeably throughout. Suitably, thefoams and foamable formulations described herein are for application toa skin surface of a mammal, suitably a human.

As used herein the term “sunscreen” refers to a formulation thatprotects the skin from sunburn and erythema by absorbing, reflecting,filtering, scattering and/or blocking ultraviolet (UV) radiation.

Ultraviolet (UV) radiation includes, UVA, UVB, UVC and combinations ofUVA, UVB and UVC light. See FIG. 1.

In exemplary embodiments, the formulations described herein furthercomprise one or more emulsion stabilizers, one or more skinconditioners, one or more emulsifiers, one or more suspending agents andwater.

Unless otherwise indicated, when referring to an amount of a componentof the formulations, the percent (%) of a component refers to the weightpercent (weight %; wt %) of the component in the formulation, where thetotal amounts of all components equal 100% by weight (100 weight %).

Suitably, the amount of emulsion stabilizer (i.e., one or more emulsionsstabilizers) in the formulations is about 0.01% to about 20%, moresuitably about 0.05% to about 15%, about 0.05% to about 10%, about 0.05%to about 8%, about 0.08% to about 7%, about 0.09% to about 6%, about0.1% to about 5%, about 0.3% to about 5%, about 0.5% to about 5%, orabout 0.5%, about 0.6%, about 0.7%, about 0.8%, about 0.9%, about 1%,about 1.5%, about 2%, about 2.5%, about 3%, about 3.5%, about 4%, about4.5% or about 5% emulsion stabilizer, including all values and rangeswithin these ranges.

Suitably, the amount of skin conditioner (i.e., one or more skinconditioners) in the formulation is about 0.01% to about 30%, moresuitably about 0.05% to about 25%, about 0.1% to about 25%, about 1% toabout 25%, about 5% to about 25%, about 10% to about 25%, about 15% toabout 25%, about 10%, about 11%, about 12%, about 13%, about 14%, about15%, about 16%, about 17%, about 18%, about 19%, about 20%, about 21%,about 22%, about 23%, about 24% or about 25%, including all ranges andvalues within these ranges.

Suitably, the amount of emulsifier (i.e., one or more emulsifiers) inthe formulations is about 0.01% to about 20%, more suitably about 0.05%to about 20%, about 0.1% to about 20%, about 0.1% to about 15%, about0.1% to about 10%, 0.5% to about 10%, about 1% to about 10%, about 2% toabout 5%, about 2.5% to about 4.5%, about 1%, about 1.5%, about 2%,about 2.5%, about 3%, about 3.5%, about 4%, about 4.5%, about 5%, about5.5%, about 6%, about 6.5%, about 7%, about 7.5%, about 8%, about 8.5%,about 9%, about 9.5% or about 10%, including all values and rangeswithin these ranges.

Suitably, the amount of suspending agent (i.e., one or more suspendingagents) is about 0.05% to about 20%, more suitably about 0.1% to about20%, about 0.1% to about 15%, about 0.1% to about 10%, about 1% to about10%, about 2% to about 6%, about 3.5% to about 5.5%, about 1%, about1.5%, about 2%, about 2.5%, about 3%, about 3.5%, about 4%, about 4.5%,about 5%, about 5.5%, about 6%, about 6.5%, about 7%, about 7.5%, about8%, about 8.5%, about 9%, about 9.5% or about 10%, including all valuesand ranges within these ranges.

Suitably, the remainder (i.e., qs) of the formulation compositionsdescribed herein is purified/sterilized/deionized water. It is routinefor those of ordinary skill in the art to determine the required weightpercent of water necessary to make up the remainder of the compositionso as to yield 100% by weight, taking into consideration the amounts ofthe other ingredients.

As described throughout, in embodiments, the amounts and particle sizesof the zinc oxide and the titanium dioxide in the formulations areselected so as to produce a minimal residual whitening effect when theformulations are applied to a skin surface. The term “minimal residualwhitening effect” is used herein to mean that, the formulations whenevenly spread onto a skin surface at a concentration of between 1-3mg/cm′, more suitably at a concentration of 2 mg/cm′, for example as setforth in the in the SPF Test Parameters, Federal Register, vol. 76, no.117, pages 35644-35645 (Jul. 17, 2011) (the disclosure of which isincorporated by reference herein in its entirety), are not visible onthe skin surface to the naked eye, i.e., they do not produce a whiteningeffect that is visible to the naked eye.

In embodiments, the present application provides formulations thatcomprise zinc oxide and titanium dioxide, with specifically selectedparticle sizes and amounts, so as to produce a minimal residualwhitening effect when the formulations are applied to a skin surface.Selection of the particle size and the amounts of the zinc oxide andtitanium dioxide is carried out by preparing the desired formulationswith the desired particle sizes and amounts of the zinc oxide andtitanium dioxide, applying the formulations to a skin surface asdescribed herein, and determining if the formulation leaves a residualwhitening effect on the skin surface.

Sub-micron scale (particles less than 1 μm in diameter) titanium dioxideworks by absorbing, reflecting and scattering UVB and some UVAradiation. Zinc oxide provides a block for ultraviolet light (UVB/UVA).It also reflects infrared from the skin, as does titanium dioxide.However, zinc oxide's ability to protect in the long UVA range, (300-400nm) is much higher than titanium dioxide. Zinc oxide absorbs, ratherthan scatters, most UVA, while titanium dioxide primarily scatters thesewavelengths. Thus, formulated in combination with titanium dioxide, zincoxide “closes the window” in the UVA range. Zinc oxide works to bothcomplement titanium dioxide's protection and extend photoprotection tothe skin where titanium dioxide may be insufficient.

Suitably, in embodiments, the formulations described herein compriseabout 1% to about 25% zinc oxide particles having a primary particlesize of less than about 50 nm. In exemplary embodiments, theformulations comprise about 3% to about 20% zinc oxide particles, moresuitably about 5% to about 15%, about 7% to about 12%, about 9% to about11%, or about 1%, about 2%, about 3%, about 4%, about 5%, about 6%,about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19% orabout 20%, zinc oxide particles.

Suitably, in embodiments, the primary particle size of the zinc oxideparticles is less than about 50 nm. As used herein, “primary particlesize” is defined as the size (suitably diameter) of disperse, individualparticles of a material without any agglomeration of or betweenparticles. Suitably, in embodiments, the zinc oxide particles have aprimary particle size that is about 10 nm to about 40 nm, more suitablyabout 10 nm to about 30 nm, or about 10 nm, about 11 nm, about 12 nm,about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm, about18 nm, about 19 nm, about 20 nm, about 21 nm, about 22 nm, about 23 nm,about 24 nm, about 25 nm, about 26 nm, about 27 am, about 28 nm, about29 nm or about 30 nm, including primary particle sizes and ranges withinthese ranges.

Suitably, in embodiments, the formulations described herein compriseabout 1% to about 25% titanium dioxide particles having a primaryparticle size of less than about 50 nm. In exemplary embodiments, theformulations comprise about 3% to about 20% titanium dioxide particles,more suitably about 5% to about 15, about 7% to about 12%, about 9% toabout 11%, or about 1%, about 2%, about 3%, about 4%, about 5%, about6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19% orabout 20%, titanium dioxide particles.

Suitably, in embodiments, the primary particle size of the titaniumdioxide particles is less than about 50 nm. Suitably, the titaniumdioxide particles have a primary particle size that is about 10 nm toabout 40 nm, more suitably about 20 nm to about 40 nm, or about 20 nm,about 21 nm, about 22 nm, about 23 nm, about 24 nm, about 25 nm, about26 nm, about 27 nm, about 28 nm, about 29 nm, about 30 nm, about 31 nm,about 32 nm, about 33 nm, about 34 nm, about 35 nm, about 36 nm, about37 nm, about 38 nm, about 39 nm, about 40 nm, including primary particlesizes and ranges within these ranges.

In embodiments, the formulations described herein comprise either zincoxide or titanium dioxide particles. In more suitable embodiments, theformulations comprise both zinc oxide and titanium dioxide particles.

As used herein an “emulsion stabilizer” refers to a composition thataids in keeping an emulsion from separating into its oil and aqueouscomponents. In embodiments, the emulsion stabilizer utilized in theformulations described herein is a naturally derived gum or a modifiedgum or natural mineral. Exemplary emulsion stabilizers include, but arenot limited to, acacia, cellulose, crystalline cellulose, gellan, guar,locust (carob) bean, xanthan, magnesium aluminum silicate, bentonite orhectorite clays and the like, including combinations thereof.

As used herein a “skin conditioner” refers to a composition that acts asa lubricant on the surface of the skin or a composition that increasesthe water content of the surface of the skin. Exemplary skinconditioners for use in the formulations include, but are not limitedto, adipate esters, alkyl benzoates, fatty acid esters of C₈ or greater,esterified erucates, laurates, neopentanoates, salicylates, stearates,triglycerides, carbonates, glycols, glycerin, mineral oils and the like,including combinations thereof.

As used herein an “emulsifier” refers to a composition that aids in theformation of an oil in water, or a water in oil, emulsion. Exemplaryemulsifiers for use in the formulations include, but are not limited to,polysorbates, ethoxylated fatty acids, fatty acids neutralized withsodium hydroxide, potassium hydroxide or amines, substituted glucosides,sodium lauryl and lauryl ether sulfates, ethoxylated esters, lecithinand lecithin derivatives and the like, including combinations thereof.

As used herein a “suspending agent” refers to a composition thatmodifies the interface between solid particles and a liquid medium toimprove the particles' resistance to coming together and falling out ofsolution. Exemplary suspending agents for use in the formulationsinclude, but are not limited to, hydroxy stearic acid,polyhydroxystearic acid, sodium polyacrylate polymers, methylmethacrylate crosspolymers and the like, including combinations thereof.

In embodiments, the formulations described herein further comprise afilm former. Suitably, the amount of the film former (i.e., one or morefilm formers) is about 0.05% to about 20%, mores suitably about 0.1% toabout 20%, about 0.1% to about 15%, about 0.1% to about 10%, about 1% toabout 10%, about 2% to about 6%, about 3.5% to about 5.5%, about 1%,about 1.5%, about 2%, about 2.5%, about 3%, about 3.5%, about 4%, about4.5%, about 5%, about 5.5%, about 6%, about 6.5%, about 7%, about 7.5%,about 8%, about 8.5%, about 9%, about 9.5% or about 10%, including allvalues and ranges within these ranges.

As used herein a “film former” refers to a composition that dries toform a thin coating on the skin to impart water resistance. Exemplaryfilm formers for use in the formulations include, but are not limitedto, alkyl methacrylate acid copolymers, acrylates/C₁₀₋₃₀ alkylmethacrylate copolymer, acrylates/octylacrylamide copolymer,polyamide-3, polyurethates-2, polyurethanes-34, polyurethanes-35, vinylpyrollidone/eicosene copolymer, tricontanyl/polyvinyl pyrollidone,dimethicone substituted polyacrylates and the like, includingcombinations thereof.

In additional embodiments, foamable sunscreen formulations are providedthat comprise:

-   -   about 1% to about 25% zinc oxide particles having a primary        particle size of less than about 50 nm;    -   about 1% to about 25% titanium dioxide particles having a        primary particle size of less than about 50 nm;    -   about 0.1% to about 10% emulsion stabilizer;    -   about 0.1% to about 25% skin conditioner;    -   about 1% to about 10% emulsifier;    -   about 0.1% to about 10% suspending agent; and    -   the remainder water.

As described herein, in embodiments, suitably the zinc oxide particleshave a primary particle size of less than about 30 nm, more suitablyabout 20 nm, or about 10 nm. In suitable embodiments, the formulationscomprise about 10% zinc oxide particles.

As described herein, in embodiments, suitably the titanium dioxideparticles have a primary particle size of about 30 nm, more suitablyabout 20 nm. In embodiments, the formulations comprise about 3% titaniumdioxide particles.

In embodiments, the emulsion stabilizers for use in the formulationsinclude, but are not limited to, microcrystalline cellulose, cellulosegum and the like, including combinations thereof.

In embodiments, the skin conditioners for use in the formulationsinclude, but are not limited to, C₁₂₋₁₅ alkyl benzoate, octyldodecylneopentanoate, butyl octyl salicylate, caprylyl glycol, glycerin and thelike, including combinations thereof.

In embodiments, the emulsifiers for use in the formulations include, butare not limited to, glyceryl stearate, ceteareth-20, polysorbate 80 andthe like, including combinations thereof.

In embodiments, the suspending agents for use in the formulationsinclude, but are not limited to, polyhydroxystearic acid, methylmethacrylate crosspolymer and the like, including combinations thereof.

As described herein, in embodiments, the formulations further comprise afilm former, suitably about 0.5% to about 3%. Exemplary film formers foruse in the formulations include, but are not limited to, polyurethane-2,polymethyl methacrylate, tricontanyl poly(vinyl pyrollidone) (PVP) andthe like, including combinations thereof.

In additional embodiments, the formulations further comprise iron oxideparticles. By controlling the purity, particle size, temperature andrate of drying during manufacture, iron oxide particles exhibit a numberof shades and tones of red, yellow, black and brown (and blends of thesebasic colors). These pigments, if incorporated at adequate concentrationand properly dispersed in not only add color to the formulations, butcan contribute significant protection to the skin over multiplewavelengths of light.

It has been determined that the addition of iron oxide particles havinga primary particle size of less than about 50 nm results in the additionof a color tone to the formulations, further diminishing any residualwhitening effect of the sunscreen formulations described herein bymatching the color of the formulations with that of the color of a skinsurface. The iron oxide particles can be of a single primary particlesize that results in a single color, or can be combinations of variousparticle sizes, including particles that produce a red, yellow, brownand/or black color, resulting in a tone of the formulation that can betailored to the desired color.

Suitably, in embodiments, the formulations described herein compriseabout 0.01% to about 10% iron oxide particles having a primary particlesize of less than about 50 nm. In embodiments, the formulations compriseabout 0.03% to about 8%, about 0.05% to about 7%, about 0.05% to about5%, about 0.1% to about 4%, about 0.1% to about 3%, about 0.1% to about2%, about 0.1% to about 1%, about 0.05%, about 0.1%, about 0.15%, about0.2%, about 0.25%, about 0.3%, about 0.35%, about 0.4%, about 0.45%, orabout 0.5% iron oxide particles.

Suitably, in embodiments, the iron oxide particles have a primaryparticles size less than about 50 nm. Suitably, the iron oxide particleshave a primary particle size that is about 10 nm to about 40 nm, moresuitably about 10 nm to about 30 nm, or about 10 nm, about 11 nm, about12 nm, about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm,about 18 nm, about 19 nm, about 20 nm, about 21 nm, about 22 nm, about23 nm, about 24 nm, about 25 nm, about 26 nm, about 27 nm, about 28 nm,about 29 nm or about 30 nm, including primary particle sizes and rangeswithin these ranges.

In additional embodiments, foamable sunscreen formulations are providedthat comprise:

-   -   about 9% to about 11% zinc oxide particles having a primary        particle size of about 20 nm;    -   about 2% to about 4% titanium dioxide particles having a primary        particle size of about 30 nm;    -   about 0.5% to about 10% emulsion stabilizer;    -   about 15% to about 25% skin conditioner;    -   about 2.5% to about 4.5% emulsifier;    -   about 3.5% to about 5.5% suspending agent;    -   about 1% to about 2.5% film former; and    -   the remainder water.

In embodiments, the formulations comprise about 10% zinc oxideparticles. In additional embodiments, the formulations suitably compriseabout 3% titanium dioxide particles. In further embodiments, theformulations suitably comprise about 10% zinc oxide particles and about3% titanium dioxide particles.

Suitably, the emulsion stabilizers for use in the formulations aremicrocrystalline cellulose, cellulose gum and combinations thereof.Suitably, the skin conditioners for use in the formulations are C₁₂₋₁₅alkyl benzoate, octyldodecyl neopentanoate, butyl octyl salicylate,caprylyl glycol, glycerin and combinations thereof. Suitably, theemulsifiers are glyceryl stearate, ceteareth-20, polysorbate 80 andcombinations thereof. Suitably, three suspending agents arepolyhydroxystearic acid, methyl methacrylate crosspolymer andcombinations thereof. Suitably, the film formers are polyurethane-2,polymethyl methacrylate, tricontanyl poly(vinyl pyrollidone) (PVP) andcombinations thereof.

In additional embodiments, the formulations further comprise about 0.05%to about 0.5% iron oxide particles having a primary particle size ofless than about 50 nm.

In further embodiments, the present application provides foamablesunscreen formulations comprising:

-   -   about 10% zinc oxide particles having a primary particle size of        about 20 nm;    -   about 3% titanium dioxide particles having a primary particle        size of about 30 nm;    -   about 1% microcrystalline cellulose and about 0.2% cellulose        gum; about 16% C₁₂₋₁₅ alkyl benzoate, about 1% octyldodecyl        neopentanoate, about 1% butyl octyl salicylate;    -   about 1.2% glyceryl stearate, about 0.5% ceteareth-20, and about        2% polysorbate 80;    -   about 1.8% polyhydroxystearic acid and about 2.7% methyl        methacrylate crosspolymer;    -   about 0.8% polyurethane-2, about 0.3% polymethyl methacrylate        and about 0.6% tricontanyl PVP film; and    -   about 50% to about 60% water and a preservative.

Suitably, such formulations further comprise about 0.05% to about 1.0%iron oxide particles having a primary particle size of less than about50 nm.

In further embodiments, provided herein are foamable sunscreenformulations comprising some portion of particles that have a primaryparticle size larger than about 100 nm. In such embodiments, pigmentsare used to result in a formulation that still produces a minimalresidual whitening effect, even though the formulations compriseparticles that are larger than 100 nm, by coloring the formulations tomatch the color of a skin surface.

In embodiments, foamable sunscreen formulations are provided thatcomprise active particles comprising zinc oxide particles and titaniumdioxide particles. The formulations also comprise about 0.1% to about10% emulsion stabilizer, about 0.1% to about 25% skin conditioner, about0.1% to about 10% emulsifier, about 0.1% to about 10% suspending agent,one or more pigments and the remainder water. Suitably the formulationscomprise at least about 5 wt % of the active particles have a primaryparticle size greater than about 100 nm. As described herein, suitablythe formulation produces a minimal residual whitening effect whenapplied to a skin surface.

As utilized herein, “active particles” is used to mean particles thateither absorb, reflect and/or scatter UVA and/or UVB light, so as toproduce a formulation that protects the skin from sunburn and erythemaby absorbing, reflecting, filtering, scattering and/or blockingultraviolet (UV) radiation. Suitably, active particles comprise zincoxide and/or titanium dioxide particles.

In embodiments, at least 1%, suitably at least 5% of the activeparticles have a primary particle size greater than about 100 nm. Thatis, at least 1% by weight of the total weight of active particlesutilized in a formulation have a primary particle size greater thanabout 100 nm. More suitably, at least about 10% of the active particleshave a primary particle size greater than 100 nm, or at least about 15%,at least about 20%, at least about 25%, at least about 30%, at leastabout 35%, at least about 40%, at least about 45%, at least about 50%,at least about 55%, at least about 60%, at least about 65%, at leastabout 70%, at least about 75%, at least about 80%, at least about 85%,at least about 90%, at least about 95%, or about 100% of the activeparticles have a primary particle size greater than about 100 nm.

In embodiments, at least about 5% of the active particles have a primaryparticle size greater than about 100 nm, suitably greater than about 200nm, greater than about 300 nm, greater than about 400 nm, greater thanabout 500 nm, greater than about 600 nm, greater than about 700 nm,greater than about 800 nm, greater than about 900 nm, or about 1.mu.m.Suitably, an upper limit for the primary particle size is about 800 nmto about 900 nm, generally where the formulations begin to feel grittyor grainy when applied to a skin surface. Thus, in embodiments, theprimary particle size is about 100 nm to about 900 nm, about 100 nm toabout 800 nm, about 100 nm to about 700 nm, about 100 nm to about 600nm, about 100 nm to about 500 nm, about 100 nm to about 400 nm, about100 nm to about 300 nm, or about 100 nm to about 200 nm, includingvalues and ranges within these size ranges. For example, titaniumdioxide particles can have a primary particle size of about 150 nm toabout 10,000 nm, with a mean of about 1100 nm and zinc oxide particlescan have a primary particle size of about 150 nm to about 550 nm, with amean of about 380 nm.

In certain embodiments, the formulations comprise active particlescomprising zinc oxide particles having a primary particle size greaterthan about 100 nm and titanium dioxide particles having a primaryparticle size less than about 50 nm in size. Titanium dioxide particleshaving a primary particle size less than about 50 nm in size aredescribed herein.

In further embodiments, the formulations comprise active particlescomprising titanium dioxide particles having a primary particle sizegreater than about 100 nm in size and zinc oxide particles having aprimary particle size less than about 50 nm in size. Zinc oxideparticles having a primary particle size less than about 50 nm aredescribed herein.

In still further embodiments, the formulations comprise active particlescomprising titanium dioxide particles having a primary particle sizegreater than about 100 nm in size and zinc oxide particles having aprimary particle size greater than about 100 nm in size.

As described throughout, in exemplary embodiments, an exemplary emulsionstabilizer is a naturally derived gum or a modified gum or naturalmineral, including an emulsion stabilizer selected from the groupconsisting of acacia, cellulose, crystalline cellulose, gellan, guar,locust (carob) bean, xanthan, magnesium aluminum silicate, bentonite orhectorite clays and/or combinations thereof.

Exemplary skin conditioners include those described throughout, such asadipate esters, alkyl benzoates, fatty acid esters of C₈ or greater,esterified erucates, laurates, neopentanoates, salicylates, stearates,triglycerides, carbonates, glycols, glycerin, mineral oils andcombinations thereof. Exemplary emulsifiers include polysorbates, fattyacids and their alkaline salts, ethoxylated fatty acids and theiralkaline salts of sodium hydroxide, potassium hydroxide and amines,substituted glucosides, sodium lauryl sulfate and lauryl ether sulfates,ethoxylated esters, lecithin and lecithin derivatives and combinationsthereof.

In embodiments, exemplary suspending agents include hydroxy stearicacid, polyhydroxystearic acid, sodium polyacrylate polymers, methylmethacrylate crosspolymers and combinations thereof.

As described herein, the formulations can further comprise about 0.1% toabout 10% film former, including alkyl methacrylate acid copolymers,acrylates/C₁₂₋₂₂ alkyl methacrylate copolymer, acrylates/octylacrylamidecopolymer, polyamide-3, polyurethane-2, polyurethanes-34,polyurethanes-35, vinyl pyrollidone/eicosene copolymer,tricontanyl/polyvinyl pyrollidone, dimethicone substituted polyacrylatesand combinations thereof.

As utilized herein, the term “pigments” means one or more dyes,particles, elements, or other agents that are used to color, tint orotherwise modify the visual appearance of a formulation as it appears ona skin surface. Suitable pigments for use in the formulations describedherein include, but are not limited to, iron oxide particles, aluminumpowder, barium sulfate, various root extracts, mineral coloring agents,and various dyes.

Suitably, as described herein, the pigments utilized in the formulationsare iron oxide particles having a primary particle size of less thanabout 50 nm. Use of iron oxide particles in the formulations comprisingactive particles having a primary particle size greater than about 100nm, results in the addition of a color tone to the formulations,diminishing or removing any residual whitening effect of the sunscreenformulations by matching the color of the formulations with that of thecolor of a skin surface. The iron oxide particles can be of a singleprimary particle size that results in a single color, or can becombinations of various particle sizes, including particles that producea red, yellow, brown and/or black color, resulting in a tone of theformulation that can be tailored to the desired color. Suitably thefoamable sunscreen formulations comprise iron oxide particles comprisingred iron oxide particles, yellow iron oxide particles or black ironoxide particles (i.e., iron oxide particles that result in these colorsdue to their particle size), and mixtures thereof. As described herein,the amount of iron oxide particles can be varied based on the desiredcoloration in the formulation, and suitably, the iron oxide particlesare present at about 0.01 wt % to about 1 wt % in the formulations.

In further embodiments, a foamable sunscreen formulation is providedcomprising:

-   -   active particles comprising zinc oxide particles having a        primary particle size of less than about 50 nm and titanium        dioxide particles having a primary particle size of greater than        about 100 nm;    -   about 0.1% to about 10% emulsion stabilizer;    -   about 0.1% to about 25% skin conditioner;    -   about 1% to about 10% emulsifier;    -   about 0.1% to about 10% suspending agent;    -   iron oxide particles; and    -   the remainder water.        As described herein, suitably at least about 5 wt % of the        active particles are greater than about 100 nm in size, and the        formulation produces a minimal residual whitening effect when        applied to a skin surface.

Suitably, the emulsion stabilizer is selected from the group consistingof microcrystalline cellulose, cellulose gum and combinations thereof.Exemplary skin conditioners include C₁₂₋₁₅ alkyl benzoate, octyldodecylneopentanoate, butyl octyl salicylate, caprylyl glycol, glycerin andcombinations thereof. Suitable emulsifiers are elected from the groupconsisting of glyceryl stearate, ceteareth-20, polysorbate 80 andcombinations thereof. Exemplary suspending agents are selected from thegroup consisting of polyhydroxystearic acid, methyl methacrylatecrosspolymer and combinations thereof.

Suitably the formulations further comprise about 0.5% to about 3% filmformer, such as polyurethane-2, polymethyl methacrylate, tricontanylpoly(vinyl pyrollidone) (PVP) and combinations thereof.

As described herein, suitably at least about 20% of the active particleshave a primary particle size greater than about 100 nm in size, moresuitably at least about 50%, or at least about 75% of the activeparticles have a primary particle size greater than about 100 nm insize.

In embodiments, the iron oxide particles comprise red iron oxideparticles, yellow iron oxide particles or black iron oxide particles,and mixtures thereof, suitably present at about 0.01 wt % to about 1 wt%.

Also provided are foamable sunscreen formulations comprising:

active particles comprising titanium dioxide particles having a primaryparticle size of less than about 50 nm and zinc oxide particles having aprimary particle size of greater than about 100 nm;

about 0.1% to about 10% emulsion stabilizer;

about 0.1% to about 25% skin conditioner;

about 1% to about 10% emulsifier;

about 0.1% to about 10% suspending agent;

iron oxide particles; and

the remainder water.

Suitably, at least about 5 wt % of the active particles have a primaryparticle size greater than about 100 nm, and wherein the formulationproduces a minimal residual whitening effect when applied to a skinsurface.

Exemplary components of the formulations and size ranges of the activeparticles are described herein.

Also provided are foamable sunscreen formulations comprising:

-   -   active particles comprising titanium dioxide particles having a        primary particle size of greater than about 100 nm and zinc        oxide particles having a primary particle size of greater than        about 100 nm;    -   about 0.1% to about 10% emulsion stabilizer;    -   about 0.1% to about 25% skin conditioner;    -   about 1% to about 10% emulsifier;    -   about 0.1% to about 10% suspending agent;    -   iron oxide particles; and    -   the remainder water.        Suitably the formulation produces a minimal residual whitening        effect when applied.

In additional embodiments, foamable sunscreen formulations are providedcomprising:

-   -   active particles comprising zinc oxide particles having a        primary particle size of less than about 50 nm and titanium        dioxide particles having a primary particle size of greater than        about 100 nm;    -   about 1% microcrystalline cellulose and about 0.2% cellulose        gum; about 16% C₁₂₋₁₅ alkyl benzoate, about 1% octyldodecyl        neopentanoate, about 1% butyl octyl salicylate;    -   about 1.2% glyceryl stearate, about 0.5% ceteareth-20, and about        2% polysorbate 80;    -   about 1.8% polyhydroxystearic acid and about 2.7% methyl        methacrylate crosspolymer;    -   about 0.8% polyurethane-2, about 0.3% polymethyl methacrylate        and about 0.6% tricontanyl PVP film;    -   iron oxide particles comprising red iron oxide particles, yellow        iron oxide particles or black iron oxide particles, and mixtures        thereof and about 50% to about 60% water.        Suitably, at least about 5 wt % of the active particles have a        primary particle size greater than about 100 nm in size, and the        formulation produces a minimal residual whitening effect when        applied to a skin surface.

In suitable embodiments, at least about 20% of the active particles havea primary particle size greater than about 100 nm, more suitably atleast about 50% of the active particles have a primary particle sizegreater than about 100 nm, or at least about 75% of the active particleshave a primary particle size greater than about 100 nm. Suitably theformulations comprise about 0.05% to about 1.0% iron oxide particleshaving a primary particle size of less than about 50 nm.

Also provide are foamable sunscreen formulations comprising:

-   -   active particles comprising titanium dioxide particles having a        primary particle size of less than about 50 nm and zinc oxide        particles having a primary particle size of greater than about        100 nm;    -   about 1% microcrystalline cellulose and about 0.2% cellulose        gum; about 16% C₁₂₋₁₅ alkyl benzoate, about 1% octyldodecyl        neopentanoate, about 1% butyl octyl salicylate;    -   about 1.2% glyceryl stearate, about 0.5% ceteareth-20, and about        2% polysorbate 80;    -   about 1.8% polyhydroxystearic acid and about 2.7% methyl        methacrylate crosspolymer;    -   about 0.8% polyurethane-2, about 0.3% polymethyl methacrylate        and about 0.6% tricontanyl PVP film;    -   iron oxide particles comprising red iron oxide particles, yellow        iron oxide particles or black iron oxide particles, and mixtures        thereof; and about 50% to about 60% water.        Suitably, at least about 5 wt % (or about 20%, about 50% or        about 75%) of the active particles have a primary particle size        greater than about 100 nm, and suitably the formulations produce        a minimal residual whitening effect when applied to a skin        surface. Suitably the formulations comprise about 0.05% to about        1.0% iron oxide particles having a primary particle size of less        than about 50 nm.

Also provided are foamable sunscreen formulations comprising:

-   -   active particles comprising titanium dioxide particles having a        primary particle size of greater than about 100 nm and zinc        oxide particles having a primary particle size of greater than        about 100 nm;    -   about 1% microcrystalline cellulose and about 0.2% cellulose        gum; about 16% C₁₂₋₁₅ alkyl benzoate, about 1% octyldodecyl        neopentanoate, about 1% butyl octyl salicylate;    -   about 1.2% glyceryl stearate, about 0.5% ceteareth-20, and about        2% polysorbate 80;    -   about 1.8% polyhydroxystearic acid and about 2.7% methyl        methacrylate crosspolymer;    -   about 0.8% polyurethane-2, about 0.3% polymethyl methacrylate        and about 0.6% tricontanyl PVP film;    -   iron oxide particles comprising red iron oxide particles, yellow        iron oxide particles or black iron oxide particles, and mixtures        thereof and about 50% to about 60% water.        Suitably the formulations produce a minimal residual whitening        effect when applied to a skin surface. In embodiments, the        formulations comprise about 0.05% to about 1.0% iron oxide        particles having a primary particle size of less than about 50        nm.

It should be noted that for formulations comprising titanium dioxideparticles and zinc oxide particles having a primary particle size largerthan about 100 nm that the formulations can also further comprisetitanium dioxide or zinc oxide particles having a primary particle sizeof less than about 100 nm, suitably less than about 50 nm, as describedherein. In additional embodiments, formulations that comprise titaniumdioxide particles and zinc oxide particles having a primary particlesize larger than about 100 nm can specifically exclude titanium dioxideparticles and zinc oxide particles having a primary particle size lessthan 100 nm or less than 50 nm.

Also provided herein are methods of preventing sun damage to a patient'sskin surface, comprising applying the foamable sunscreen formulationsdescribed throughout topically to the surface of the skin.

As used herein “preventing sun damage” means that the formulationsdescribed throughout provide a sufficient barrier to the UVA and/or UVBradiation of the sun so as to reduce, limit or suitably eliminate,damage (i.e., degradation, mutations, skin burn) to cells, tissues,nucleic acids (DNA/RNA), etc. caused by the exposure of a skin surfaceto such radiation.

In exemplary embodiments, the foamable sunscreen formulations areapplied at least once a day. Suitably, such formulations are applied onan as-needed basis throughout the day according to a patient's exposureto sun or other forms of UVA/UVB radiation.

As described herein, the foamable sunscreen formulations are suitablyapplied to any skin surface, including for example, the arms, face,legs, legs, chest, trunk or hands.

In further embodiments, foamable sunscreen formulations are providedthat consist of or consist essentially of the recited components at therecited amounts.

In formulations that consist essentially of the recited ingredients,such formulations specifically exclude other sun-blocking agents, as theaddition of such agents would be considered a material alteration tosuch formulations and is thus excluded from such formulations thatconsist essentially of the recited ingredients at the recited amounts.

It will be readily apparent to one of ordinary skill in the relevantarts that other suitable modifications and adaptations to the methodsand applications described herein can be made without departing from thescope of any of the embodiments. The following examples are includedherewith for purposes of illustration only and are not intended to belimiting.

EXAMPLES Example 1: Exemplary Formulations Comprising Particles Lessthan 100 nm

Below are examples of stable/non-separating formulations containing onlyzinc oxide particles, only titanium dioxide particles, and a combinationof both zinc oxide and titanium dioxide particles as active ingredients.Suitably, the zinc oxide have a primary particle size of 20 nm and thetitanium dioxide particles have a primary particle size of 30 nm.

Formulation #1 #2 #3 Ingredient Wt % Wt % Wt % Water qs to 100% qs to100% qs to 100% Microcrystalline Cellulose 1.0 1.0 1.0 Cellulose Gum 0.20.2 0.2 Polyurethane-2 0.8 0.8 0.8 Polymethyl Methacrylate 0.3 0.3 0.3C₁₂₋₁₄ Alkyl Benzoate 16.0 16.0 16.0 Octodecyl Neopentanoate 1.0 1.0 1.0Butyl Octyl Salicylate 1.0 1.0 1.0 Cetearyl Alcohol 1.5 1.5 1.5 GycerylStearate 1.3 1.3 1.3 Ceteareth-20 0.5 0.5 0.5 Polysorbate 80 2.0 2.0 2.0Polyhydroxystearic acid 1.8 1.8 1.8 Glycereth-26 0.5 0.5 0.5 TricontanylPVP 0.5 0.5 0.5 Zinc Oxide 10.0 — 10.0 Titanium Dioxide — 3.0 3.0 MethylMethacrylate Crosspolymer 2.8 2.8 2.8 Preservative 1.0 1.0 1.0

Zinc Oxide was obtained from Kobo Products, Inc., South Plainfield, N.J.Titanium Dioxide was obtained from Sensient Technologies, Milwaukee.Wis.

These formulations when aerosolized and applied to the skin, do notleave a white residue visible to the naked eye, i.e., they produce aminimal residual whitening effect.

Below are examples of stable/non-separating formulations containing onlyzinc oxide particles, only titanium dioxide particles, and a combinationof both zinc oxide and titanium dioxide particles as active ingredients,and also containing iron oxide pigments to add color to the formulationto match appropriate skin tones. Suitably, the zinc oxide particles havea primary particle size of 20 nm and the titanium dioxide particles havea primary particle size of 30 nm.

Formulation #4 #5 #6 Ingredient Wt % Wt % Wt % Water qs to 100% qs to100% qs to 100% Microcrystalline Cellulose 1.0 1.0 1.0 Cellulose Gum 0.20.2 0.2 Polyurethane-2 0.8 0.8 0.8 Polymethyl Methacrylate 0.3 0.3 0.3C₁₂₋₁₄ Alkyl Benzoate 16.0 16.0 16.0 Octodecyl Neopentanoate 1.0 1.0 1.0Butyl Octyl Salicylate 1.0 1.0 1.0 Cetearyl Alcohol 1.5 1.5 1.5 GycerylStearate 1.3 1.3 1.3 Ceteareth-20 0.5 0.5 0.5 Polysorbate 80 2.0 2.0 2.0Polyhydroxystearic acid 1.8 1.8 1.8 Glycereth-26 0.5 0.5 0.5 TricontanylPVP 0.5 0.5 0.5 Zinc Oxide 10.0 — 10.0 Titanium Dioxide — 3.0 3.0 MethylMethacrylate Crosspolymer 2.8 2.8 2.8 Preservative 1.0 1.0 1.0 IronOxide Red CI 77491 0.12 0.12 0.12 Iron Oxide Yellow CI 77492 0.3 0.3 0.3Iron Oxide Black 0.05 0.05 0.05

Zinc Oxide was obtained from Kobo Products, Inc., South Plainfield, N.J.Titanium Dioxide was obtained from Sensient Technologies, Milwaukee,Wis.

These formulations when aerosolized and applied to the skin, do notleave a white residue visible to the naked eye, i.e., they produce aminimal residual whitening effect. The red, yellow, and black iron oxidepigments can be adjusted in any proportion or eliminated entirely asillustrated above to match skin tones based on the Fitzpatrick SkinPrototype Scale. The Fitzpatrick scale is the common reference indermatology for classifying skin tone from very light (SPT I) to verydark (SPT VI). This scale is given below:

Classification of Fitzpatrick's Skin Prototypes SPT Basic Skin ColorResponse to Sun Exposure I Pale White Does not tan, burns easily IIWhite Tan with difficulty, burns easily III White Tan after initialsunburn IV Lt. Brown/Olive Tan easily V Brown Tan easily VI Black Becomedarker

Example 2: Exemplary Formulations Comprising Particles Greater than 100nm

Provided below are formulations utilizing active particles comprisingzinc oxide particles having a primary particle size greater than about100 nm and titanium dioxide particles having a primary particle size ofabout 30 nm. These formulations demonstrate the use of iron oxideparticles to match several skin tones on the Fitzpatrick Skin Prototypeclassification by modifying the amounts or red, yellow and black ironoxide particles.

Formulation #7 #8 #9 Ingredient Wt % Wt % Wt % Water qs to 100% qs to100% qs to 100% Microcrystalline Cellulose 1.0 1.0 1.0 Cellulose Gum 0.20.2 0.2 Polyurethane-2 0.8 0.8 0.8 Polymethyl Methacrylate 0.3 0.3 0.3C₁₂₋₁₄ Alkyl Benzoate 16.0 16.0 16.0 Octodecyl Neopentanoate 1.0 1.0 1.0Butyl Octyl Salicylate 1.0 1.0 1.0 Cetearyl Alcohol 1.5 1.5 1.5 GycerylStearate 1.3 1.3 1.3 Ceteareth-20 0.5 0.5 0.5 Polysorbate 80 2.0 2.0 2.0Polyhydroxystearic acid 1.8 1.8 1.8 Glycereth-26 0.5 0.5 0.5 TricontanylPVP 0.5 0.5 0.5 Zinc Oxide (>100 nm) 10.0 10.0 10.0 Zinc Oxide (<100 nm)— — — Titanium Dioxide (>100nm) — — — Titanium Dioxide (28-32 nm) 3.03.0 3.0 Methyl Methacrylate Crosspolymer 2.8 2.8 2.8 Preservative 1.01.0 1.0 Iron Oxide Red CI 77491 0.13 0.36 0.65 Iron Oxide Yellow CI77492 0.23 0.72 1.43 Iron Oxide Black 0.03 0.19 0.21

The mean primary particle size of the zinc oxide particles was about 380nm, with a range of about 150 nm to about 550 nm.

Zinc Oxide was obtained from BASF Corp., Florham Park, N.J. TitaniumDioxide was obtained from Sensient Technologies, Milwaukee, Wis.

Results in matching the skin tone to the Fitzpatrick Skin Prototypeclassification are given in the table below.

Formulation Fitzpatrick Skin Number Shade Prototype Match 7 Light I toII * 8 Medium II to III* 9 Darker Greater than III*These formulations utilize 76.9% of the total amount of Titanium Dioxideand Zinc Oxide (active particles) having a primary particle size greaterthan about 100 nanometers. Skin tone can be matched to any desired shadeby adjusting the amounts and combinations of the iron oxide pigments.

Provided below are formulations utilizing active particles comprisingtitanium dioxide particles having a primary particle size greater thanabout 100 nm and zinc oxide particles having a primary particle size ofabout 30 nm. These formulations demonstrate the use of iron oxideparticles to match several skin tones on the Fitzpatrick Skin Prototypeclassification by modifying the amounts or red, yellow and black ironoxide particles.

Formulation #10 #11 #12 Ingredient Wt % Wt % Wt % Water qs to 100% qs to100% qs to 100% Microcrystalline Cellulose 1.0 1.0 1.0 Cellulose Gum 0.20.2 0.2 Polyurethane-2 0.8 0.8 0.8 Polymethyl Methacrylate 0.3 0.3 0.3C₁₂₋₁₄ Alkyl Benzoate 16.0 16.0 16.0 Octodecyl Neopentanoate 1.0 1.0 1.0Butyl Octyl Salicylate 1.0 1.0 1.0 Cetearyl Alcohol 1.5 1.5 1.5 GycerylStearate 1.3 1.3 1.3 Ceteareth-20 0.5 0.5 0.5 Polysorbate 80 2.0 2.0 2.0Polyhydroxystearic acid 1.8 1.8 1.8 Glycereth-26 0.5 0.5 0.5 TricontanylPVP 0.5 0.5 0.5 Zinc Oxide (>100 nm) — — — Zinc Oxide (30 nm) 10.0 10.010.0 Titanium Dioxide (>100 nm) 3.0 3.0 3.0 Titanium Dioxide (28-32 nm)— — — Methyl Methacrylate Crosspolymer 2.8 2.8 2.8 Preservative 1.0 1.01.0 Iron Oxide Red CI 77491 0.13 0.36 0.65 Iron Oxide Yellow CI 774920.23 0.72 1.43 Iron Oxide Black 0.03 0.19 0.21

The mean primary particle size of the titanium dioxide particles wasabout 1100 nm, with a range of about 150 nm to about 10,000 nm.

Zinc Oxide was obtained from Kobo Products, Inc., South Plainfield, N.J.Titanium Dioxide was obtained from Kobo Products, Inc., SouthPlainfield, N.J.

Results in matching the skin tone to the Fitzpatrick Skin Prototypeclassification are given in the table below.

Formulation Fitzpatrick Skin Number Shade Prototype Match 10 Light I toII * 11 Medium II to III* 12 Darker Greater than III*These formulations utilize 23.1% of the total amount of Titanium Dioxideand Zinc Oxide (active particles) having a primary particle size greaterthan about 100 nanometers. The overall residual whiteness is less thanthat of formulations #'s 7, 8 & 9 above. Skin tone can be matched to anydesired shade by adjusting the amounts and combinations of the ironoxide pigments.

Provided below are formulations utilizing active particles comprisingtitanium dioxide particles having a primary particle size greater than100 nm and zinc oxide particles having a primary particle size greaterthan 100 nm. These formulations demonstrate the use of iron oxideparticles to match several skin tones on the Fitzpatrick Skin Prototypeclassification by modifying the amounts or red, yellow and black ironoxide particles.

Formulation #13 #14 #15 Ingredient Wt % Wt % Wt % Water qs to 100% qs to100% qs to 100% Microcrystalline Cellulose 1.0 1.0 1.0 Cellulose Gum 0.20.2 0.2 Polyurethane-2 0.8 0.8 0.8 Polymethyl Methacrylate 0.3 0.3 0.3C₁₂₋₁₄ Alkyl Benzoate 16.0 16.0 16.0 Octodecyl Neopentanoate 1.0 1.0 1.0Butyl Octyl Salicylate 1.0 1.0 1.0 Cetearyl Alcohol 1.5 1.5 1.5 GycerylStearate 1.3 1.3 1.3 Ceteareth-20 0.5 0.5 0.5 Polysorbate 80 2.0 2.0 2.0Polyhydroxystearic acid 1.8 1.8 1.8 Glycereth-26 0.5 0.5 0.5 TricontanylPVP 0.5 0.5 0.5 Zinc Oxide (>100 nm) 10.0 10.0 10.0 Zinc Oxide (30 nm) —— — Titanium Dioxide (>100 nm) 3.0 3.0 3.0 Titanium Dioxide (28-32 nm) —— — Methyl Methacrylate Crosspolymer 2.8 2.8 2.8 Preservative 1.0 1.01.0 Iron Oxide Red CI 77491 0.13 0.36 0.65 Iron Oxide Yellow CI 774920.23 0.72 1.43 Iron Oxide Black 0.03 0.19 0.21

The mean primary particle size of the zinc oxide particles was about 380nm, with a range of about 150 nm to about 550 nm.

The mean primary particle size of the titanium dioxide particles wasabout 1100 nm, with a range of about 150 nm to about 10,000 nm.

Zinc Oxide was obtained from BASF Corp., Florham Park, N.J. TitaniumDioxide was obtained from Kobo Products, Inc., South Plainfield, N.J.

Results in matching the skin tone to the Fitzpatrick Skin Prototypeclassification are given in the table below.

Formulation Fitzpatrick Skin Number Shade Prototype Match 13 Light I toII * 14 Medium II to III* 15 Darker Greater than III*

These formulations utilize 100.0% of the total amount of TitaniumDioxide and Zinc Oxide (active particles) having a primary particle sizegreater than about 100 nanometers, therefore the overall residualwhiteness is darker than that of formulations described above(Formulations #:7-12). Skin tone can be matched to any desired shade byadjusting the amounts and combinations of the iron oxide pigments.

It is to be understood that while certain embodiments have beenillustrated and described herein, the claims are not to be limited tothe specific forms or arrangement of parts described and shown. In thespecification, there have been disclosed illustrative embodiments and,although specific terms are employed, they are used in a generic anddescriptive sense only and not for purposes of limitation. Modificationsand variations of the embodiments are possible in light of the aboveteachings. It is therefore to be understood that the embodiments may bepracticed otherwise than as specifically described.

What is claimed is:
 1. A sunscreen formulation consisting essentiallyof: a. about 1 wt % to about 25 wt % zinc oxide particles having aprimary particle size of about 5 nm to about 500 nm; b. about 1 wt % toabout 25 wt % titanium dioxide particles having a primary particle sizeof about 5 nm to about 500 nm; c. about 0.1 wt % to about 10 wt %emulsion stabilizer; d. about 0.1 wt % to about 25 wt % skinconditioner; e. about 0.1 wt % to about 10 wt % suspending agent; and f.the remainder water, wherein the formulation is free of an emulsifier,and wherein the formulation produces a minimal residual whitening effectwhen applied to a skin surface.
 2. The sunscreen formulation of claim 1,wherein the zinc oxide particles have a primary particle size of about10 nm to about 50 nm.
 3. The sunscreen formulation of claim 1,comprising about 10 wt % to about 15 wt % zinc oxide particles.
 4. Thesunscreen formulation of claim 1, wherein the titanium dioxide particleshave a primary particle size of about 10 nm to about 50 nm.
 5. Thesunscreen formulation of claim 1, comprising about 1 wt % to about 10 wt% titanium dioxide particles.
 6. The sunscreen formulation of claim 1,wherein the emulsion stabilizer is selected from the group consisting ofmicrocrystalline cellulose, cellulose gum, and combinations thereof. 7.The sunscreen formulation of claim 1, wherein the skin conditioner isselected from the group consisting of C₁₂₋₁₅ alkyl benzoate,octyldodecyl neopentanoate, butyl octyl salicylate, caprylyl glycol,glycerin, and combinations thereof.
 8. The sunscreen formulation ofclaim 1, wherein the suspending agent is selected from the groupconsisting of polyhydroxystearic acid, methyl methacrylate crosspolymer,and combinations thereof.
 9. The sunscreen formulation of claim 1,further consisting essentially of about 0.5 wt % to about 3 wt % of filmformer.
 10. The sunscreen formulation of claim 1, further consistingessentially of about 0.01 wt % to about 1 wt % iron oxide particles. 11.A sunscreen formulation consisting essentially of: a. about 1 wt % toabout 50 wt % active particles having a primary particle size of about 5nm to about 500 nm; b. about 0.1 wt % to about 10 wt % emulsionstabilizer; c. about 0.1 wt % to about 25 wt % skin conditioner; d.about 0.1 wt % to about 10 wt % suspending agent; and e. the remainderwater, wherein the formulation is free of an emulsifier, and wherein theformulation produces a minimal residual whitening effect when applied toa skin surface.
 12. The sunscreen formulation of claim 11, wherein thewt % of active particles is about 1 wt % to about 15 wt %.
 13. Thesunscreen formulation of claim 11, wherein the active particles have aprimary particle size of about 10 nm to about 100 nm.
 14. The sunscreenformulation of claim 11, wherein the emulsion stabilizer is selectedfrom the group consisting of microcrystalline cellulose, cellulose gum,and combinations thereof.
 15. The sunscreen formulation of claim 11,wherein the skin conditioner is selected from the group consisting ofC₁₂₋₁₅ alkyl benzoate, octyldodecyl neopentanoate, butyl octylsalicylate, caprylyl glycol, glycerin, and combinations thereof.
 16. Thesunscreen formulation of claim 11, wherein the suspending agent isselected from the group consisting of polyhydroxystearic acid, methylmethacrylate crosspolymer, and combinations thereof.
 17. The sunscreenformulation of claim 11, further consisting essentially of about 0.5 wt% to about 3 wt % film former, wherein the film former is selected fromthe group consisting of polyurethane-2, polymethyl methacrylate,tricontanyl poly(vinyl pyrollidone) (PVP), and combinations thereof. 18.The sunscreen formulation of claim 11, further consisting essentially ofabout 0.01 wt % to about 1 wt % iron oxide particles.
 19. A sunscreenformulation comprising: a. about 1 wt % to about 25 wt % zinc oxideparticles having a primary particle size of about 5 nm to about 500 nm;b. about 1 wt % to about 25 wt % titanium oxide particles having aprimary particle size of about 5 nm to about 500 nm; c. about 0.1 wt %to about 5 wt % microcrystalline cellulose and about 0.1 wt % to about 5wt % cellulose gum; d. about 15 wt % to about 20 wt % C₁₂₋₁₅ alkylbenzoate, about 0.1 wt % to about 5 wt % octyldodecyl neopentanoate,about 0.1 wt % to about 5 wt % butyl octyl salicylate, and about 0.1 wt% to about 5 wt % glyceryl stearate; e. about 0.1 wt % to about 5 wt %polyhydroxystearic acid; f. about 0.1 wt % to about 3 wt %polyurethane-2, about 0.1 wt % to about 3 wt % polymethyl methacrylate,about 0.1 wt % to about 3 wt % tricontanyl PVP film, and about 0.1 wt %to about 5 wt % methyl methacrylate crosspolymer; and g. about 50 wt %to about 60 wt % water, wherein the formulation is free of anemulsifier, and wherein the formulation produces a minimal residualwhitening effect when applied to a skin surface.
 20. The sunscreenformulation of claim 19, further comprising about 0.01 wt % to about 1wt % iron oxide particles.